Fixed load thermomotive flasher with normally engaged contacts



31, 1967 A. F. BLEIWEISS ETAL 3,350,527

FIXED LOAD THERMOMOTIVE FLASHER WITH NORMALLY ENGAGED CONTACTS Filed March 21, 1966 REAR INVENTORS ARTHUR E BLEIWEISS GEORGE COLOMBO BY JOHN B. DICKSON ATTORNEYS United States Patent 3,350,527 FIXED LOAD TI'IERMOR'EOEEVJL NORMALLY ENGAGED CONTACTS Arthur F. Bleiweiss, New York, and George Colombo,

East Roclraway, N.Y., and .lohn B. Dickson, Clewiston F521,, assignors to Lehigh Valley Industries, Inc., a corporation of Delaware Filed Mar. 21, 1966, Scr. No. 535,933 13 Claims. (Cl. 200-122) This application is a continuation-in-part of copending application Serial No. 230,050, filed October 12, 1962 now Patent No. 3,246,181, issued April 12, 1966. This invention relates to flashers generally of the type kllOWI] as thermomotive flashers commonly used in automotive vehicle signalling systems for flashing the signal lamps of vehicles to indicate left or right turns or a hazard or emergency situation.

The invention is more specifically directed to the socalled snap element type flasher which snaps between a restored and a constrained position on expansion and contraction of a pull element as a result of heating and cooling of the pull element.

A principal object of this invention is the construction of improved flashers of the fixed or specific load type wherein the moveable contact is removed from the pull element and located on the snap element to remove certain stresses from the pull element to thereby improve its life operating characteristics.

Other objects and advantages of the invention will in part be obvious and will in specification.

Generally speaking, in accordance with the invention, a snap element type flasher flashes the vehicle lamps connected in the load circuit by the cyclical opening and closing of cintacts in response to a snapping action of the snap element. The snap element, which may be in the form of a vane has secured thereto a pull element or pull ribbon of preselected resistance which, when cool, holds the vane in a constrained position. When current flows through the pull ribbon, it heats and expands thereby allowing the vane to snap to a restored position. A pair of contacts, one fixed and one mounted on the vane for movement therewith, control the state of the circuit. When an electrical circuit is completed from the source of potential to the signal lamps, the selected lamps are illuminated as a result of current flow through the flasher and normally closed contacts. The full load current also flows through the pull ribbon causing it to heat and expand and snap the vane to the restored, contacts open position whereupon the circuit is broken and the pull ribbon cools to snap the vane back to the constrained, contacts closed position whereupon the cycle repeats so long as the signal switch remains closed.

Since the full load current flows through the pull ribbon, the flasher is what has been deemed a fixed or specific load flasher. In other words, the optimum flashing rate, in accordance with S.A.E. specifications for example, is obtained by proper correlation of the heating, cooling and other characteristics of the pull ribbon related to the load current of the signal lamps for which the flasher is designed. If the load current should change, the full load applied to the flasher pull ribbon would change the cycling rate. The flasher will therefore cycle at the designed rate only on the application of a specific or fixed load.

Fixed or specific load flashers are generally known in the art. However, as shown by U.S. Patent 2,756,304, issued to James W. Welsh on July 24, 1956, such flashers provide for mounting of the moveable contact on the pull ribbon. While such flashers perform satisfactorily, the shocks applied to the pull ribbon as a result of contact engagement and pull ribbon expansion and contraction,

FLASHER WITH part be apparent from the u can reduce pull ribbon life or change the flasher operating characteristics. By removing the contact from the pull ribbon, the simplified construction of the fixed load flasher is maintained with the unexpected improvement in life operating characteristics. Additionally, by eliminating any weld or interruption of the continuity of the longitudinal axis of the pull ribbon along which it expands and contracts, even greater life operating characteristics have been experienced.

The invention accordingly comprises the features of construction, combination of elements, and arrangement of parts which will be exemplified in the constructions hereinafter set forth, and the scope of the invention will be indicated in the claims.

For a fuller understanding is had to the following description taken in connection with the accompanying drawing, in which:

FIG. 1 is a schematic representation of one type of flasher constructed in accordance with the invention, connected into a typical signalling system;

FIG. 2 is a schematic representation of another form of flasher construction; and

FIG. 3 is a schematic representation of still another form of flasher construction.

Referring now to FIG. 1, an embodiment of the instant invention is disclosed in conjunction with what may be termed a fixed load flasher having normally closed contacts. With the normally closed contacts, the signal lamps are lighted the instant the circuit is completed by closure of the appropriate switch, the turn signal switch for example, with flashing resulting from the opening and closing of the flasher contacts.

The flasher schematically depicted in FIG. 1 incorporates a vane and pull ribbon of a type well known in the art such as that disclosed in aforesaid U.S. Patent 2,756,304. Thus a detailed description of the vane construction, pull ribbon attachment and mounting arrangement is deemed unnecessary. A contact is mounted fixed with respect to a moveable contact carried by the vane with the contacts making and break-ing a circuit is a result of snapping of the vane between its two positions. The normal position of the vane is its constrained position when the pull ribbon is cool, and in this condition the contacts are closed. On heating and expansion of the pull ribbon, the vane snaps to a restored position to open or break the contacts.

In the flasher schematically shown in FIG. 1, the moveable contact is carried by the vane while the circuit for heating the pull ribbon connects directly to the pull ribon as disclosed in the aforesaid U.S. application Serial No. 230,050, filed Oct. 12, 1962, of which this application is a continuation-in-part. A typical automotive signalling system is shown consisting of a grounded source of potential shown as battery 11 and a set of signal lights 12. In passenger vehicles, there is usually provided one left and one right front signal light and one or more left and right rear signal lights. In the example shown, each of the left and right rear signals consists of three bulbs which is representative of the trend in passenger vehicle signalling systems. A turn signal switch is schematically represented by the indicia TS for selective connection of the circuit to either the left or right signal lamps for selectively signalling a left or right turn. In the example shown, the load seen by the flasher remains constant whether a left or right turn is being signalled, so long as all bulbs remain operative, and the flasher characteristics are selected to provide the desired flashing rate for the number and load current of the bulbs shown for the left or right side of the vehicle.

For simplicity, the battery is shown as being connected to the input terminal X and the signal lamps connected of the invention, reference to the load terminal L. The flasher to be hereafter described is generally provided with corresponding terminals for connection into the circuitry.

The flasher is indicated generally at 13. A vane 14 is supported by a fixed mounting 15 and is provided with a pull ribbon 16 for releasing and constraining the vane in response to heating and cooling of the pull ribbon as described above. A moveable contact 17 is carried by the vane proximate to and normally engaged with a fixed contact 18. Moveable contact 17 is electrically connected to the vane while fixed contact 18 is electrically connected to load terminal L through a conductor 19. A flexible connector 21 electrically connects the pull ribbon to input terminal X. Flexible connector 21 may be of any flexible and electrically conductive construction, such as a length of braided wire or metal ribbon with one end being suitably connected to pull ribbon 16 by any suitable means, such as welding. Flexible connector 21 is preferably connected to the pull ribbon at approximately the longitudinal center thereof so as to divide the load current through the pull ribbon. While the fixed contact is depicted as connected to the load terminal and the pull ribbon to the input terminal reversal of the connections would not in any way change the operation of the flasher. Also, one of the terminals could be connected through a switched resistance circuit to ground as shown in copending application Serial No. 2303050.

The operation of the circuit of FIG. 1 may now be described. When the turn signal switch TS is operated to signal either a left or right turn, a closed circuit is completed from battery 11 through the four signal lamps on one side of the vehicle to illuminate the signal lamps. The circuit is through the flasher from input terminal X through the flexible connection 21, the pull ribbon 16, vane 14, normally closed contacts 17 and 18, conductor 19 and the load terminal L. As the current passes through the pull ribbon, the resistance thereof effects a heating of the pull ribbon causing it to expand to allow the constrained vane to snap to its restored position and thereby physically open contacts 17 and 18 to break the circuit. On breaking of the circuit, the signal lamps are extinguished and the pull ribbon is allowed to cool. When the pull ribbon has cooled sufliciently, it returns the vane to the constrained position thereby closing contacts 17 and 18 and again illuminating the signal lamps. Again the pull ribbon heats to expand and, as will be apparent, the flasher cycles to continuously flash the signal lamps so long as the turn signal switch is in an operative position.

In accordance with known flasher construction, vane 14 has a fixed mounting point at 15 and the snapping of the vane between the restored and the constrained position causes movement of that portion of the vane carrying contact 17 toward and from fixed contact 18. The movement of the vane also effects a movement of the pull ribbon and the provision of the flexible connector 21 avoids any irnpediment to the movement of the pull ribbon.

The removal of the moveable contact from the pull ribbon, while maintaining the known flasher heating cireuit, has demonstrated substantial improvements in uniformity of operation over the life of the flasher and has, in many instances, extended the useful life of the flasher. The element which controls the snap action of the flasher is the pull ribbon which is formed of an electrically conductive, relatively thin resistance strip capable of heating on application of a potential thereacross and expanding as a result of such heating. The pull ribbon is thereby subjected to substantial strain as a result of its cyclical heating and cooling, expansion and contraction. While prior art flashers have performed satisfactorily, the location of the moveable contact on the pull ribbon increases the stresses cyclically applied to the pull ribbon, especially during the impact which occurs on engagement of the moveable contact with the fixed contact. The improved and unexpected results of flasher operation became evident during testing of the above described flasher. In the improved flasher shown in FIG. 1, the only element contacting the pull ribbon between its ends is flexible connector 21 which, once attached to the pull ribbon, remains in contact throughout. Any suitable means may be utilized to aflix an end of flexible connector 21 to the pull ribbon, the only requirement being that good elec trical connection is maintained throughout the life of the flasher. Thus the connector could be wrapped around the pull ribbon or crimped thereto or welded thereto, such as by spot welding. While the welding of an end of the flexible connector to the pull ribbon upsets the molecular pattern and uniform stress concentrations, improved life operating characteristics result. Even greateradvantages are derived from a connection which omits the weld. Wrapped or crimped connections have demonstrated good results as has an arrangement wherein the pull ribbon is devoid of the application of any stresses thereto over its entire length along its longitudinal axis. Such an arrangement is shown in FIG. 2 which will now be described.

FIG. 2 differs from FIG. 1 primarily with respect to the pull ribbon configuration, the vane, fixed mounting, and contacts being the same as described in connection with FIG. 1. In FIG. 2, a pull ribbon 31 is formed of a strip of conductive, resistance material. If desired the strip may be of substantially uniform width except at an area preferably at its center. The pull ribbon is formed with a tab 32 extending transversely from the longitudinal axis of the pull ribbon. A flexible conductive ribbon 33 is welded at one end to tab 32, and is suitably connected, at its other end, to input terminal X. From FIG. 2 it is quite apparent that the longitudinal axis of pull ribbon 31 is free of all extraneous stresses which would normally result from connecting a flexible connector to the pull ribbon. While a weld on the longitudinal axis of the pull ribbon is perhaps the most severe form of pull ribbon disturbance, wrapping or crimping can also affeet the pull ribbon. External factors do affect the uniformity of heating and cooling rates, expansion and contraction of the pull ribbon throughout its life and, by minimizing such external factors, the desired operating characteristics will be maintained for a longer period of time.

Thus, the utilization of a pull ribbon with a tab as shown in FIG. 2 substantially reduces the application of external factors. As before, the electrical connection to the pull ribbon must be flexible to permit free movement of the vane and pull ribbon during snapping thereof. FIG. 2 discloses a conductive ribbon by way of example, but any other suitable flexible connection would be satisfactory.

As shown in FIGS. 1 and 2, the electrical connection to the pull ribbon is preferably at the center thereof in order that the load current travelling through the pull ribbon and vane to the contacts be uniformly divided and result in substantially uniform heating along the pull ribbon. While the flasher would operate satisfactorily with other than a central connection, non-uniform heating of the pull ribbon would result from unequal current distribution in the pull ribbon and this could adversely affect the useful operating life of the pull ribbon.

A further embodiment wherein the longitudinal pull axis of the pull ribbon is free of extraneous stresses is disclosed in FIG. 3. A pull ribbon 41 has a substantially elongated tab 42 extending therefrom. The pull ribbon and tab is blanked out as a single unit, with the tab being bent along a smooth are as at 43 to impart the requisite flexibility to the assembly to thereby provide an integrated flexible circuit connector. The tab is then directly connected to the X terminal and a true stress free pull ribbon results.

As discussed above, the primary purpose of the invention is to minimize the application of external factors to the pull ribbon of a fixed or specific load flasher which carries full load current. This is accomplished by removing the moveable contact from the pull ribbon and mounting it on the vane and providing flexible means for the circuit connection to the pull ribbon. Arrangements other than those described are within the foregoing invention once the moveable contact has been removed from the pull ribbon.

It will thus be seen that the objects set forth above, among those made apparent from the preceding description, are efliciently attained and, since certain changes may be made in the above constructions without departing from the spirit and scope of the invention, it is intended that all matter contained in the above description or shown in the accompanying drawing shall be interpreted as i1- lustrative and not in a limiting sense.

It is also to be understood that the following claims are intended to cover all of the generic and specific features of the invention herein described, and all statements of the scope of the invention which, as a matter of language, might be said to fall therebetween.

What is claimed is:

1. A fixed load thermomotive flasher comprising a fixed mounting, a snap element, a pull element, a fixed contact and a movable contact, said snap element and fixed contact being fixedly mounted on said fixed mounting, said pull element being physically and electrically connected to said snap element, said contacts adapted for making Or breaking a circuit in response to heating Or cooling of the pull element, and a flexible circuit connector electrically connected to said pull element for connecting said flasher to one side of said circuit, said fixed contact electrically connecting said flasher to the other side of said circuit, said moveable contact being carried by said snap element and normally in engagement with said fixed contact when said pull element is in a cooled condition.

2. A fixed load thermomotive flasher comprising a fixed mounting, a vane supported from said fixed mounting, a pull ribbon secured to said vane, a moveable contact carried by said vane, a fixed contact fixedly supported with respect to said fixed mounting, said contact being normally in engagement and adapted for separation in response to heating of said pull ribbon, a first terminal, a flexible circuit connector electrically connected to said pull ribbon and connected to said first terminal and a second terminal electrically connected to said fixed contact.

3. A thermomotive flasher as claimed in claim 2 wherein said pull ribbon is connected at its ends to said vane, said flexible circuit connector being secured to said pull ribbon centrally thereof with respect to said ends of said pull ribbon.

4. A thermomotive flasher as claimed in claim 2 wherein one end of said flexible circuit connector is welded to said pull ribbon.

5. A thermomotive flasher as claimed in claim 3 wherein one end of said flexible circuit connector is welded to said pull ribbon.

6. A thermomotive flasher as claimed in claim 2 wherein said moveable contact is electrically and mechanically affixed to said vane remote from the location of the vane support fixed mounting.

7. A thermomotive flasher as claimed in claim 2 wherein the major length of the pull ribbon is of substantially uniform width with respect to its longitudinal axis except at the area to which is secured said flexible circuit connector, at least one part of said pull ribbon including a portion extending rom said uniform width, said flexible circuit connector being secured to said portion to leave the longitudinal area of uniform width free of external connections.

8. A thermomotive flasher as claimed in claim 7 wherein said portion comprises a tab extending beyond said uniform width, said flexible circuit connector being secured to said tab.

9. A thermomotive flasher as claimed in claim 8 wherein said tab is located centrally of said pull ribbon with respect to the ends thereof.

10. A thermomotive flasher as claimed in claim 7 wherein said flexible circuit connector is welded at one end of said portion.

11. A thermomotive flasher as claimed in claim 2 wherein the major length of the pull ribbon between its points of attachment to said vane is free of external connections, at least one part of said pull ribbon including a portion extending therefrom, said flexible circuit connector being secured to said portion.

12. A thermomotive flasher as claimed in claim 2 wherein the major length of the pull ribbon between its points of attachment to said vane is free of external connections, at least one part of said pull ribbon including a portion extending therefrom, said portion including means to impart flexibility thereto for defining said flexible circuit connector.

13. A fixed load thermomotive flasher comprising a fixed mounting, a snap element, a pull element, a fixed contact and a movable contact, said snap element and fixed contact being fixedly mounted on said fixed mounting, said pull element being physically and electrically connected to said snap element, said contacts adapted for disengagement or engagement in response to heating or cooling of the pull element for making or breaking a circuit, and at least first and second circuit connections, said first circuit connection being physically and electrically connected to said pull element, said second circuit connection being physically and electrically connected to said fixed contact, said movable contact being carried by said vane and normally in engagement with said fixed contact when said pull element is in a cooled condition.

References Cited UNITED STATES PATENTS 2,822,444 2/1958 Colombo et al. 200-113 X 3,256,406 6/1966 Wojcik 200-113 2,166,238 7/1939 Davis 200-137 2,639,190 5/ 1953 Sitzer 200113 X BERNARD A. GILHEANY, Primary Examiner,

A. LEWITTER, Assistant Examiner 

2. A FIXED LOAD THERMOMOTIVE FLASHER COMPRISING A FIXED MOUNTING, A VANE SUPPORTED FROM SAID FIXED MOUNTING, A PULL RIBBON SECURED TO SAID VANE, A MOVABLE CONTACT CARRIED BY SAID VANE, A FIXED CONTACT FIXEDLY SUPPORTED WITH RESPECT TO SAID FIXED MOUNTING, SAID CONTACT BEING NORMALLY IN ENGAGEMENT AND ADAPTED FOR SEPARATION IN RESPONSE TO HEATING OF SAID PULL RIBBON, A FIRST TERMINAL, A FLEXIBLE CIRCUIT CONNECTOR ELECTRICALLY CONNECTED TO SAID PULL RIBBON AND CONNECTED TO SAID FIRST TERMINAL AND A SECOND TERMINAL ELECTRICALLY CONNECTED TO SAID FIXED CONTACT. 